As a general output format of sensor devices, such as a pressure sensor device and a current sensor device, there are an analog output format and a digital output format. The former format outputs a signal outputted from a sensor element as an analog signal (generally in voltage) to the external side of the sensor device, after performing analog signal processing, such as amplification. The latter format outputs a signal outputted from a sensor element as a digital value to the external side of the sensor device, after performing analog-to-digital (A/D) conversion. Usually, a required output format of a sensor device differs according to an application, in which the sensor device is employed. Therefore, in the past, a circuit of the output stage is suitably designed according to the output format required, or, after mounting a circuit of the output stage, which is operable in both formats (a circuit for analog output, and a circuit for digital output), the circuit is selectively used, depending on the output format required. For this reason, cost for developing the circuit and cost for producing a chip, on which the circuit is fabricated, are increased, and also development period is increased.
Patent Document 1 discloses a sensor device, which employs a successive comparison A/D converter device, making it possible to integrate an analog output circuit and a digital output circuit into one device by using a digital-to-analog (D/A) converter circuit, which is a component of the A/D converter device. If such a sensor device is employed, it is possible to support both an analog output format and a digital output format. Accordingly, it is possible to realize a small-sized sensor device.
(Patent Document 1) JP Patent No. 4284851
Generally, according to the type of a sensor device and the type of application, in which the sensor device is employed, there are a variety of specifications of resolution of A/D conversion and D/A conversion. On the other hand, a successive approximation A/D converter device cannot change its resolution, without changing the circuit configuration thereof. Therefore, when adopting the technology disclosed in Patent Document 1, it is necessary to change the circuit configuration of a D/A converter circuit in the A/D converter device, according to the resolution required. That is, in the technology disclosed in Patent Document 1, it is necessary to change the circuit configuration according to the specifications of the resolution of A/D conversion and D/A conversion. Therefore, the development cost and the development period are necessarily increased.